在Android上使用.NET MAUI进行手势操作时,可能会发现滑动手势不起作用或者出现其它异常.
下面给出一个定义一个自定义Renderer,在其中使用GestureDetector和OnTouchListener来自定义手势操作。
public class MyPanGestureHandler : ViewRenderer
{
private readonly GestureDetector _gestureDetector;
private bool _disposed;
public MyPanGestureHandler(Context context, PinchImageView element) : base(context)
{
_gestureDetector = new GestureDetector(Context, new GestureListener(element));
}
protected override void OnElementChanged(ElementChangedEventArgs e)
{
base.OnElementChanged(e);
if (e.OldElement != null)
{
SetOnTouchListener(null);
}
if (e.NewElement != null)
{
SetOnTouchListener(new TouchListener(_gestureDetector));
}
}
protected override void Dispose(bool disposing)
{
if (_disposed)
{
return;
}
if (disposing)
{
SetOnTouchListener(null);
}
_disposed = true;
base.Dispose(disposing);
}
private class GestureListener : GestureDetector.SimpleOnGestureListener
{
private readonly PinchImageView _element;
public GestureListener(PinchImageView element)
{
_element = element;
}
public override bool OnScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY)
{
_element.PanGesture?.Invoke(_element, new PanUpdatedEventArgs(GestureStatus.Running, distanceX, distanceY));
return true;
}
public override bool OnFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY)
{
_element.PanGesture?.Invoke(_element, new PanUpdatedEventArgs(GestureStatus.Completed));
return true;
}
}
private class TouchListener : Java.Lang.Object, IOnTouchListener
{
private readonly GestureDetector _gestureDetector;
public TouchListener(GestureDetector gestureDetector)
{
_gestureDetector = gestureDetector;
}
public bool OnTouch(Android.Views.View v, MotionEvent e)
{
return _gestureDetector.OnTouchEvent(e);
}
}
}
此示例演示了如何在.NET MAUI中处理滑动手势。请注意,将上述代码示例中的PinchImageView替换为你正在使用的视图类型。